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Oil Separators & Vent lines

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99610708054
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Oil separator in sump. Porsche Boxster / 996 / 997

porsche
(2 per car)

Fits:
Porsche 986 Boxster 1997-05
Porsche 987 Boxster 2.7L / 3.2L 2005-06
Porsche 996 C2 / C4 / C4S 1998-05
Porsche 997 Carrera 3.6L / 3.8L 2005-08

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Diagram ref no 4

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99610708054
99610708054

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99710703801
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Oil Separator main centre.
1 per car

porsche

Fits:
Porsche 997 3.8L Carrera 2S / 4S 2005-08

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Diagram Ref No 1.

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99710703801
99710703800
99710703801
56764

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99710703801/2
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Oil Separator main centre.
Oil Separator - Main Centre unit - is a direct-fit replacement for the factory crankcase ventilation system component used on Porsche 911 (997) Carrera 3.8L 2S / 4S engines. This separator plays a vital role in maintaining crankcase pressure equilibrium by separating oil mist from blow-by gases before routing clean air back into the intake manifold.

Fits:
Porsche 997 3.8L Carrera 2S / 4S 2005 - 2008

Diagram Ref No 1.

• Function: Separates oil vapours from crankcase gases to prevent oil ingestion
• Position: Engine – main centre, crankcase ventilation housing
 Benefits: OE-style fit, improved oil vapor separation, durable diaphragm construction
 Installation: Direct-fit replacement; verify hose routing and seals during reassembly

Over time, the oil separator’s diaphragm and housing can degrade from heat cycling, oil vapour, and pressure changes, leading to vacuum leaks, oil smoke, or excessive consumption.

Replace this unit when:
 You see oil residue or smoke from the exhaust or intake
• The engine shows rough idle, whistling sounds, or high vacuum
• Oil consumption has increased significantly
 During engine service or PCV system maintenance

Replacing restores balanced crankcase pressure, prevents oil ingestion, and maintains clean combustion — ensuring your Porsche 997’s 3.8L engine performs at its best.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99710703801
99710703800
99710703801

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99710602802
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Return line for oil separator. 

porsche

Fits:
Porsche 997.1 Carrera 2S / 4S 3.8L

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Diagram ref no 14




Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99710602802
99710602802
99710602801

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About Oil Separators & Vent lines

Oil Separators & Vent Lines – Maintain Clean Airflow and Engine Efficiency

The oil separator and vent line system plays a critical role in your Porsche’s crankcase ventilation process. By separating oil vapour from the engine’s blow-by gases, these components ensure only clean air is returned to the intake system — reducing emissions, preventing carbon build-up, and maintaining consistent engine performance.

At Design911, we stock a complete range of oil separators, breather hoses, and vent lines designed for Porsche engines of all generations. Manufactured from high-grade, heat- and oil-resistant materials, these components are built to handle the demands of high-performance driving, ensuring a tight seal, proper ventilation, and long-lasting reliability.

Whether you’re maintaining a daily-driven 911 or servicing a track-ready Cayman, our oil separators and vent lines help preserve your engine’s efficiency, longevity, and power output.

What Do Oil Separators & Vent Lines Do?

The oil separator and vent system controls crankcase pressure and removes oil vapour from the air circulating inside the engine.

Core Functions:

  • Separate oil vapour from crankcase gases, keeping intake air clean.
  • Prevent oil from entering the intake manifold or combustion chamber.
  • Maintain stable crankcase pressure for efficient engine breathing.
  • Reduce harmful emissions and extend engine life.
  • Support consistent power delivery and smooth idle performance.

By ensuring clean ventilation and stable pressure, these components protect your Porsche’s engine from oil contamination and performance loss.

Why Do Oil Separators & Vent Lines Fail?

Over time, heat cycles, oil vapours, and pressure fluctuations cause these parts to degrade or clog, leading to poor ventilation and increased oil consumption.

  • Common Causes of Failure Include:
  • Clogged internal membranes in the separator.
  • Cracked or brittle vent lines from heat and age.
  • Oil leaks from worn seals or connections.
  • Vacuum leaks, causing rough idling or poor throttle response.
  • Build-up of sludge or condensation within breather hoses.

Typical symptoms include increased oil consumption, blue exhaust smoke, rough idle, or oil leaks around the intake area, all indicating the need for inspection or replacement.

Why Replace Components?

Replacing a faulty oil separator or vent line restores proper crankcase ventilation and prevents costly engine issues like carbon build-up or oil contamination. Our precision-engineered replacements are designed for accurate fitment and long-term durability, ensuring your Porsche operates efficiently.

Key Benefits:

  • Restores clean airflow and stable crankcase pressure.
  • Reduces oil leaks and smoke from the exhaust.
  • Improves fuel efficiency and throttle response.
  • Constructed from high-quality, heat- and oil-resistant materials.
  • Direct-fit compatibility with Porsche engines.
  • Ideal for maintenance, rebuilds, or performance tuning.

Upgrading or replacing your oil separator and vent lines is essential for maintaining your Porsche’s smooth performance and clean emissions system.

Highlights:

  • High-quality Porsche oil separators, breather hoses, and vent lines.
  • Ensures clean crankcase ventilation and stable engine pressure.
  • Reduces oil leaks, smoke, and carbon build-up.
  • Durable construction for long-term reliability.
  • Direct-fit for Porsche 911, Cayman, Boxster, Panamera & more.
  • Perfect for preventive maintenance or full engine rebuilds.

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